I am in the process of gutting a 5'x8' bathroom. I have removed the wall tile, mortar and lathing that ran roughly 4' high and plaster and lathing to the ceiling. The tub will be next. Thankfully, the ceiling has remained pristine throughout the demolition process. I have come to realize that there is roughly a 1" space between the finished ceiling, window frame and door frame to the exposed wall studs. How would I go about filling the 1" space? I am leaning toward doubling up on 1/2" moisture resistant Sheetrock for the walls to fill the gap.